Combination mill and under-reamer for oil wells



c. 5, 1954 R, E. CLARK, JR 2,590,897

COMBINATION MILL AND UNDER-REAMER FOR OIL WELLS f me@ Nov. 27, 195o s'sheets-sheet 1 Rober f. C/OrgJr:

A T TORNE Y d. 5, E954 R, E. CLARK, JR 2590897 COMBINATION MILL AND UNDER-REAMER FOR OIL WELLS Filed Nov. 27, 1950 3 Sheets-Shee'fl 2 Rober- E. C/or/gJn INVENTOR.

Wj@ M A T TOR/VE Y c. 5, 954 R, E, CLARK, JR 2,690,897

COMBINATION MILL AND UNDER-REAMER FOR OIL WELLS Filed Nov. 27, 1950 3 Sheets-Sheet 3 INVENTOR. BY M A T TOR/vf y Rober f E. Clar/gh Patented Oct. 5, 1954 UNITED STATES ATENT OFFICE COMBINATIGN MILL AND UNDER-BEAMER FOR OIL WELLS 5 Claims.

This invention relates to a combination cutting, milling, and under-reaming tool for wells, as oil wells, such Itool being adapted to be installed on the end of a tubing string, as the rotary drill string, to rst cut through the casing of the cased well bore, and then to mill a Window in the casing as the under-reamer is extended to underream the formation outwardly of the window.

It is an object of this invention to provide a combination cutting, milling and under-reaming tool adapted to be installed on the end of a tubular string, as the drill string in a well bore, to cut through and then mill a window through the well bore casing and to under-ream the formation outwardly of the window.

It is a further object of this invention to apply pressure to fluid in the tubular string above the tool to operate on a means to extend both the milling cutters and under-reamers of the tool and at the same time to supply the fluid to lubricate the operation of such cutters and under- ISameIS.

It is a further object of this invention to provide a low pressure area within the bottom of the tool into which the cutter and under-reamer operating means or plunger extends, so that there is a pressure dierential between the upper portion of the operating means or plunger, and the lower portion thereof, thereby insuring that the plunger moves downwardly to positively extend er travel to indicate the end of the milling and under-reaming operation by a pressure drop indicated at the top of the well.

It is yet another object of this invention to provide a tool of this class which is adapted to have pressure fluid Washed through the base thereof when the low pressure area therein is punctured at the end of the milling and under-reaming operation.

`Other and further objects will be apparent when the specification is considered in connection with the drawings in which:

Fig. 1 is a sectional elevation prior to the insertion of the operating plunger.

Fig. 2 is a sectional elevation prior to the in- 2 sertion of the operating plunger, such elevation being taken at 90 from that of Fig. 1.

Fig. 3 is a sectional plan View taken along line 3-3 of Fig. 1.

Fig. 4 is a sectional plan view taken along line d-li of Fig. 1.

Fig. 5 is a sectional plan view taken along line 5--5 of Fig. 1.

Figs. 6 is a sectional plan view taken along line 6 6 of Fig. 1.

Fig. 7 is a sectional plan view taken along line I-l of Fig. 2.

Fig. 8 is a sectional elevation, similar to the section shown in Fig. 1 and showing the underreamers in the process of being extended to under-ream.

Fig. 9 is a sectional elevation, similar to the sectional elevation shown in Fig. 2, showing the milling cutters in the process of cutting into the casing.

Fig. l0 is a sectional elevation similar to the elevation shown in Fig. 1 which shows the underreamers fully extended.

Fig. 11 is a sectional elevation similar to the sectional elevation shown in Fig. 2 which shows the milling cutters fully extended after a windoW has been cut.

Fig. 12 is a sectional elevation of the bottom of the well in which the casing terminates.

In Fig. 1 a tubular string, as a drill string I, extends from the top of the well into the well bore 2 which is enclosed by the casing 3. A tool body is adapted, as by the thread engagement 5, for connection to the drill string I. The head B of the body 4 is recessed at the top to receive therein the bumper 'l which is made of a resilient material to fit within the bore 8 of the body. The bore 8 extends downwardly and communi- Cates at 9 with the openings IIJ and II. These openings have pins or axles I2 extending thereacross and under-reamers I4 are pivotally mounted thereon. These under-reamers have straight outer faces I5, as shown in Fig. 1, and bevelled inner faces I6 to serve as cam surfaces.

In order to cut the formation to be underreamed, the under-reamers I4 have hardened cutting surfaces provided, as the diamonds I'I. Below the under-reamers in the openings I0 and II are pivotally mounted, as on the pins I8, the cam arms I9, which have the cam rollers 20 pivotally mounted on the pins 2l thereof.

As shown in Fig. 3, the passages 23 and 24 are provided to extend tangentially outwardly from the bore 8. The bushings 25 are provided to be inserted in the enlarged inner portions 23 and B 24' of the passages 23 and 20, respectively, to limit the orifices provided to various required sizes.

As shown in Figs. 1 and 2 below the passages 23 and 24 are provided the passages 21 and 28 which extend diagonally downwardly from the bore 8 into the openings 29 and 33 to direct iiuid, as` drilling mud, onto the cutting edges 3i and 32, respectively, of the milling cutters 33 and 34 respectively. These milling cutters are pivotally mounted on the pins or axles 35 which extend across the openings 29 and 33. The cutting edges 3| and 32 are temperedv or surfaced with a hardened material as diamonds.

Before the tool fi, at the end of a drill string I, is lowered into the well, shear pins 3l are inserted through the under-reamers I4 and into the body on either side thereof to hold these elements in position, and retracted from any possible contact with the casing wall 3. Shear pins 36 also are provided to hold the milling cutters 33 and 34 out of contact with the casing wall 3.

When the drill string I has been lowered to position the tool il at a desired elevation in the well, as an elevation adjacent an oil producing sand, the plunger Q is dropped from the top of the well down the bore dI of the drill string. This plunger lll) will seat upon the bumper 'i and will be restrained at this position until a force is applied from above to force the plunger downwardly. This force is supplied by iilling the bore 4I of the drill string I with a fluid, as drilling mud, and by applying a force at the top of the well, as the power of a pump, to exert a pressure upon the top surface 33 of the plunger 130. After the plunger has passed through the bumper 'I the outer surface dl thereof is in contact with the O-ring seal 45' to restrain the fluid from passing further downwardly.

To maintain a balance to accommodate any pressure built up in the drill string bore ll-I, in excess of that pressure required to move the plunger 40 downwardly, the passages 23 and 2d operate on the dashpot principle to by-pass part of the delivered fluid out into the annular space 55 between the drill string I and the casing 3.

As the fluid forces the plunger downwardly it rst contacts the inner corners 45 of the milling cutters 33 and 34 tobegin moving them outwardly. At this point it should be noticed that the shear pins 36v have been severed at thev beginning of outward movement of the milling cutters. As this is done the O-ring seal 5.5 is in contact with the outer plunger surface lill, but the passages 2T and' 28' are being uncovered. This increases the outow of fluid into the annulus 55, under the dash-pot principle, and at the same time supplies drilling mud' through the passages 21 and 28' to lubricate the milling cutters.

In case it may be desired to limit the ilow of huid through the openings 2l and 28, the bushings IQ and 5B may be installed therein as shown inY Figs. 2, 9, and 1l, thereby restricting the flow passage through such opening. Such bushings, of various inner diameters, may be provided to control the various volumetric ilow requirements which it may be necessary to obtain for satisfactory operation.

When the plunger 40 first contacts the milling cutters, they are moved outwardly froml the position shown in Fig. 2 to contact the wall of the casing 3. As the drill string I is rotatedv the milling cutters begin to cut a groove in the casing wall, and continued rotation, as the iiuid pressure forces the plunger further downwardly, increases the depths of this groove until the casing wall is nally cut through and severed. After this is accomplished, the drill string I is lowered as it is rotated and the milling cutters, fully extended by the downward movement of the plunger, as shown in Fig. 9, mill a window in the well bore or rather enlarge the width of the severance of the casing 3.

While the plunger surface 44 is in contact with the milling cutter corners 46 to extend them to cut through the casing wall 3, the seating surface 'I5 of the plunger and the plunger parts therebelow are adjacent to, and are passing by the under-reamers I4 in spaced relation therefrom.

After the plunger 0, in its downward passage responsive to fluidl pressure, has contacted the milling cutters 33 and 34 and the window described hereinabove has been cut, it further contacts the rollers 20 of the cam arms I9 to force these arms against the under or inner sides IG of the under-reamers to force them outwardly into the window made by the milling cutters, as best shown in Fig. 8. The initial contact severs the shear pins 3l to permit this outward movement of the under-reamers.

The rotation of the drill string I then rotates the under-reamers against the formation outwardly of the casing 3 to under-ream or enlarge an area outwardly of the window while the milling cutter continues to enlarge the window as shown in Fig. 11 when this iigure is considered in relation to Fig. l0. This enlargement is made for the purpose of exposing producing veins or crevices through which fluid, as oil, may flow into the annular space 55 between the casing 3 and drill string I.

As' shown in Fig. 12, prior to the beginning of the milling and under-reaming operation, the casing 3 has been cemented at the bottom 6I and cement has been forced upwardly therearound in the annular space 55 into which the casing has been originally inserted. This cement extends substantially above the place where the window is to be cut and approximately to the top of the well. When the window 51 has been cut and an area 58 of concrete removed outwardly thereof by the milling cutters, the uid which iiows from the formation 59' enters the under-reamed space 6E) and ills the space below the drill string I and tool 4 to the cemented bottom 6I of the casing 3. The huid, as oil, then must naturally rise upwardly in the casing 3 above the tool 4 and around the drill string' I.

When the lower portion or end 65 of the tool' 6 is considered, the O-ring seal 66, the diaphragm 61, the chamber 68, andV the retaining ring 69, and the diaphragm 'I0 are pointed out as the means which preventsa substantial pressure to.

oppose a downward motion of the plunger 40.

When the spear end. II,r of the plunger 40, having the point I2 thereon, moves through the seal B6, a limited further travel causes it to puncture the diaphragm 6'! to enter the chamber 68. This chamber 68 is originally sealed atv atmospheric pressure so that at the time of puncturing the diaphragm 61, the spear end 'II moves.

into a low pressure area as compared with the area above the seal 66, the. contact of the. spear end periphery 'I3 serving at this time, by this. contact with the O-ring sealr 66, to maintain thisv differential. This diierential is necessary as otherwise the downward motion of the plunger would be opposed by a pressure equal to that in the iluid` thereabove with the result of effective opposition to the downward travel of the plunger.

After the spear end 1l punctures the diaphragm 61 it continues to move further downwardly until it nally comes in contact with the diaphragm T0. This occurs at the point when the under-reamers I4 are fully extended. At this time the milling cutters 33 and 34 have been milling away in cutting the window in the casing 3 as the drill string has been both lowered and rotated. Finally, the last downward movement of the plunger 40 forces the spear point 'l2 of the spear end through the diaphragm and at the same time the spear surface i3 breaks contacts with the O-ring seal 66. Also, the conical seating surface I5 of the plunger 4@ seats on the ribs 16 which are radially spaced about the countersunk bore 11. Furthermore the plunger 40 moves out of surface contact with the O-ring seal 45.

When the plunger is at its lowest point of travel and is seated on the ribs lr6, fluid, as drilling mud, can wash downwardly through the tool 4 and through the openings between ribs i3 and will pass through the chamber B8 and around the spear end 1| and flow out the broken diaphragm 10. This free circulation of fluid which follows the puncturing of the diaphragm 'l0 and the equalizing of pressure within the well, is a desirable feature at this stage of operation as it is preferable, especially with under-reaming at completion, to wash through the tool and to circulate uid fully to clean the under-reamed spaces.

This invention combines in one structure the equipment required to cut through the casing wall and mill a window in the casing, with the equipment conventionally used separately to under-raam an area around the opened casing. Heretofore, it has been necessary to make one trip into the well with the milling cutter means installed on the drill string, then remove the drill string and follow by making another trip in the well with the under-reaming means installed on the drill string. Additionally, conventional means have not employed pressure of a fluid. as drilling mud in most cases, to operate either the milling cutter means or the underreaming means.

It can be seen that an invention of this type saves at least one trip into the well for each window which has to be cut. The employment of such an invention also results in a considerable cost saving over devices which require some mechanical means at the top of the well to operate the milling cutter or the under-reamer in addition to the rotating force applied to the drill string.

It is particularly pointed out that the form of invention disclosed is not the only structure capable of carrying out the function and theory of this invention. The chamber 68, sealed at atmospheric pressure, might be eliminated and the bottom of the tool may consist of an opening of considerable size. Such a construction is recommended where deposits of sand might settle within the tool to interfere with its operation, particularly with the retraction of the plunger 40. In such modification as may be employed to aviod this occurrence the vertical spacing between the ports 23 and 21 should bear such a relation to the shape and dimensions of the plunger that a sequence of occurrences as follows may take place.

First, there will be a pressure drop when the top portion of the plunger surface 44 begins clearing the ports 23. Such beginning of clearance takes place ata time when the milling cutters 33 and 34 have cut through the casing 3. Then, by the time the plunger begins operating to extend the under-reamers I4 the top portion of the plunger surface 44 begins to uncover the passages 2'! and 28 to permit fluid to lubricate the milling cutters 33, 34. The uncovering of the passages 21 and 28 is naturally accompanied by a second pressure drop indicated at the top of the well. In such a modification, the passages 21 and 28 may have an opening through the bore 8 of considerable vertical length and width and therefore the maximum pressure drop which will be indicated at the top of the well will occur at maximum extension of the under-reamers.

The structures are also even included within the concept of this invention which may operate the milling cutters to full extension rst and then the under-reamers thereafter in sequence. This can be accomplished simply by providing a longer plunger and a longer body with the under-reamer cams spaced in the body a distance below the milling cutters so that the plunger will not begin l extending the under-reamers into the window until the milling cutters are at full extension.

It is obvious that the plunger l5, by the shape of its head, is engageable by any of the many conventional type of grapples or retrieving tools now employed in oil well practice. Such a device is lowered on a wire line until it strikes upon, and is guided over the plunger head by virtue of its shape and the shape of the plunger head, and by the pull of gravity on the weight of the retrieving tool. Such tool has locking parts urged yieldably inwardly which lock under the head of the plunger so that the plunger may be withdrawn from the tool body 2. Then it is obvious that, when the drill string I is raised. the milling cutters and under-rearners will pivot inwardly and swing by gravity within the tool body 2.

Broadly, this invention considers a method and structure of providing a tool including both milling cutters and under-reamers therein, such tool being installed on a drill stem or operating string and positioned in the well at a desired level. The invention then considers operating the tool at such level by force, as by fluid pumped from the top of the well, so that a window may be made in the casing and an annular space underreamed outwardly of the window to expose a greater surface area of producing formation to the flow of fluid as oil, such results being obtainable by one trip into the well of the tool and operating string.

What is claimed is:

1. With a rotary tubular string in a cased well bore adapted to have fluid under pressure supplied thereinto from the top of the well, the combination of, a tubular tool body having recess means therein and adapted for connection to the body of said string, milling cutter means and underreamer means each separately pivotally mounted in said recess means in vertically spaced apart relation, a plunger in said body and operable responsive to said fluid pressure to successively engage the cutter means and the underreamer means and to rst extend said milling cutters to cut through and then to mill a window in said casing after the cutter means has been fully extended and to extend said underreamer means through said window to underream the formation outwardly of the casing as said window in being milled.

2. With a rotary tubular string ina cased Well bore adapted to have iluidl under pressure supplied thereinto from the top of,A the well, the com-A bination of, a tubular tool body havingl recess:

means therein and adapted for connection tothe body of said string, milling cutter means` andl underreamer means each separately pivotally mounted one above the other in said recess meansa plunger in said body having acamming formation thereon, means toproject said'. plunger in steps to swing said cutter andi underreamer about their pivots by successive'camming: formation engagement therewith, rst to extend said milling cutters to cut a window in saidY casing,

and after extension of the cutter to extend said underreamer means through said window to underream the formation outwardly of the casing.

3. With a rotary tubular string in a cased' well bore adapted to have fluid under recorded pressure supplied thereinto. from the top; of the well, the combination of, a tubular tool body having recess means therein and adapted for connection to the body of said string, milling cutter means and underreamer means spaced vertically one above the other and each separately pivotally mounted in said recess means for projection from a retracted position, a plunger in said body and operable responsive to said fluid pressure, to rst. project said milling cutters to cut a window in said casing, and to thereafter project said underreamer means through said window to underream the formation outwardly of the casing, a frangible diaphragm and a seal in said body below said recess means and a closure in saidY body therebelow so that said diaphragm and said closure enclose a space in said body at substantially atmospheric pressure, saiddiaphragm being puncturable by the weight of saidv plunger and said seal sealing around the plunger to enclose the lower end of said plunger in said space.

4. With a rotary tubular string in a cased well bore adapted to have fluid under pressure supplied thereinto from the top o1" the well, the combination' of, a tubular tool body having a continuous axial passage therethrough and lateral recess means therein and adapted for connection to the body of said string, millingl cutter means and under-reamer means each separately pivotally mounted in said recessmeans one above theother, and means operable responsive to said fluid pressure to first, swing said millingl cutters to outwardly projected position to cut through and then to rnillV a window in said casing,` and thereafter to swing saidv under-reamer means throughsaid window: to1under-ream the forma.- tion-` outwardly of" the casing as said Window is being milled, said4 tool providing a seat for saidV cutter and: under-reamer extending means at the end of under-ream extension, said seat being adapted to. permit the continued ow of uid through said passage.

5'. With av rotary tubular string in a cased well bore adapted to have fluidY under pressure suppliedthereinto from the top of the well, the combination; of',l a. tubular toolv body having recess.

means therein andadaptedfor connection to the body of.' said string; milling cutter means and underreamer means, in vertically* spaced' apart relation and' each. separately, pivotally mounted in said recess means. for movement from a retracted to. an extended position, a plunger in said body operable responsive to said uid pressure and engageable, rst, with said milling cutter meansto project the, same into` cutting relation with said casing to cutl a window therein and thereafter to project, sai-d underreamer means through the window tounderream the formation outwardly of the casing, a frangible diaphragm and a seal in said body belowsaid recess means,

a closure in saidV body therebelow so that said diaphragm and said closure enclose a space in saidbody at substantially atmospheric pressure, said diaphragm being puncturable by the weight of said plunger and saidseal sealing around the plunger to. enclose the lower end of saidA plunger in said space, said plunger havingv a seal by-pass portion in inoperative position above said. seal while milling and underreaming and the pressure of said fluid foreingsaidl plunger downwardly to puncture said closure and bringl the by-pass portion into operative position below said seal as milling and underreaming are concluded whereby said fluid may wash axially through said tool.

References Cited in the le of this patent.

UNITED STATES PATENTS Number Name Date 1,478,306 Sweetman Dec. 18, 1923 1,752,092 Kapeluchnikoi Mar. 25, 1930 1,839,588' Raymond Jan. 5, 1932 1,857,616 Baker May 10,v 1932 2,108,330 Ellis Feb. 15, 1938 2,110,913 Lowrey Mar. 15, 1938 2,246,711' Barrett et al. June 24, 1941 2,324,679l Cox July 20, 1943 2,389,235 Harrison Nov. 20, 1945 

